Send standard, MIME and batch email; manage scheduled sends
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openapi: 3.2.0
info:
title: SMTP2GO EMAILS API
version: 3.0.4
description: The SMTP2GO v3 REST API for sending transactional email and SMS, managing sender domains and single sender emails, SMTP users, API keys, IP allow lists and IP auth, templates, webhooks, suppressions, subaccounts, dedicated IPs, email archive, activity search and delivery statistics. Every operation is a POST (with a PATCH variant on two paths) carrying a JSON body; authentication is an API key supplied in the X-Smtp2go-Api-Key header or as an api_key field in the request body.
contact:
name: SMTP2GO Support
url: https://support.smtp2go.com/
termsOfService: https://www.smtp2go.com/terms/
x-harvest:
source: https://developers.smtp2go.com/mcp
method: MCP tools/call get-endpoint, one call per path+method, assembled verbatim
harvested: '2026-08-13'
server_info:
name: SMTP2GO-API-Docs
version: 3.0.4
note: SMTP2GO does not publish a single fetchable OpenAPI URL; the ReadMe registry path answers 429 to non-browser clients. The provider's own remote MCP server returns the authoritative OpenAPI 3.1.0 fragment for each endpoint anonymously, and those 73 fragments are merged here without modification.
servers:
- url: https://api.smtp2go.com/v3
description: Regionless
- url: https://us-api.smtp2go.com/v3
description: US Region
- url: https://eu-api.smtp2go.com/v3
description: EU Region
- url: https://au-api.smtp2go.com/v3
description: AU Region
security:
- sec0: []
tags:
- name: EMAILS
description: Send standard, MIME and batch email; manage scheduled sends
paths:
/email/batch:
post:
tags:
- EMAILS
summary: Send a batch of emails
description: Send a batch of emails
operationId: send-email-batch
requestBody:
content:
application/json:
schema:
type: object
required:
- emails
example:
emails:
- to:
- Jane Jones <jane@example.com>
sender: John Smith <john@example.com>
subject: 'My Test Email #1'
html_body: <h1>Test <img src="cid:mypicture.jpg" /></h1>
text_body: Test
attachments:
- filename: report.pdf
mimetype: application/pdf
fileblob: bm90IGFjdHVhbGx5IGEgcGRm...
inlines:
- filename: mypicture.jpg
mimetype: image/jpeg
url: https://myserver.com/mypicture.jpg
- to:
- Jane Jones <jane@example.com>
sender: John Smith <john@example.com>
subject: 'My Test Email #2'
html_body: <h1>Test <img src="cid:mypicture.jpg" /></h1>
text_body: Test
attachments:
- filename: report.pdf
mimetype: application/pdf
fileblob: bm90IGFjdHVhbGx5IGEgcGRm...
inlines:
- filename: mypicture.jpg
mimetype: image/jpeg
url: https://myserver.com/mypicture.jpg
schedule: 2026-01-01 12:00:00 +1300
properties:
emails:
type: array
description: An array of email objects to schedule
items:
type: object
required:
- sender
- to
- subject
properties:
sender:
type: string
description: The name and email address to send from, in the format `Name <name@example.com>`
to:
type: array
description: An array of names and email addresses (up to 100) to send to, in the format `Name <name@example.com>`
items:
type: string
cc:
type: array
description: An array of names and email addresses (up to 100) to CC, in the format `Name <name@example.com>`
items:
type: string
bcc:
type: array
description: An array of names and email addresses (up to 100) to BCC, in the format `Name <name@example.com>`
items:
type: string
subject:
type: string
description: The subject of the email to be sent
html_body:
type: string
description: 'A HTML encoded email body. Either html_body or text_body is required if template_id is not passed.<br><br> <strong>Warning:</strong><ul><li>To correctly track clicking of URLs you must: <ul><li>Enable click tracking for the API key</li> <li>Insert a full anchor HTML element (not just the URL)</li> <li>Include "https://" at the start of the HREF property</li> </ul></ul>'
text_body:
type: string
description: A plain text email body. Either html_body or text_body is required if template_id is not passed
custom_headers:
type: array
description: An array of custom header objects to be applied to the email. For example, a `Reply-To` email can be specified here, with header `Reply-To` and value `name@example.com`. For sending purposes the following headers are not allowed `Content-Type`, `Content-Transfer-Encoding` and `MIME-Version`.
items:
properties:
header:
type: string
description: Custom header to add to the email
value:
type: string
description: Custom header value to set
required:
- header
- value
type: object
attachments:
type: array
description: An array of attachment objects to be attached to the email
items:
properties:
filename:
type: string
description: The filename to use for this binary data
fileblob:
type: string
description: The Base64 encoded binary data of the file. Required if no url is specified.
mimetype:
type: string
description: The mimetype of the binary data
url:
type: string
description: A URL pointing to the attachment data. The data is directly retrieved by our system, and cached for fast re-use for 24 hours. Required if no fileblob is specified
required:
- filename
type: object
inlines:
type: array
description: An array of images to be inlined into the email. Use an image in content as `<img src="cid:filename" />`
items:
properties:
filename:
type: string
description: The filename to use for this binary data
fileblob:
type: string
description: The Base64 encoded binary data of the file. Required if no url is specified.
mimetype:
type: string
description: The mimetype of the binary data
url:
type: string
description: A URL pointing to the attachment data. The data is directly retrieved by our system, and cached for fast re-use for 24 hours. Required if no fileblob is specified
required:
- filename
type: object
template_id:
type: string
description: The ID of the template you wish to use
template_data:
type: string
description: 'When a template_id is provided, include the pass-through values in the format `{"variable1": "value1", "variable2": "value2"}`'
format: json
schedule:
type: string
description: A timestamp that when passed allows you to schedule an email for sending. Must be in the future and within the next 3 days.<br />The api response will include a `schedule_id` property which can then be used alongside webhooks (An `X-Smtp2go-Schedule-Id` header is added to the sent email corresponds to this id). A total of 50,000 emails can be queued at any one time.
responses:
'200':
description: An array of `email_id/schedule_id` values coinciding with the same order as the request payload.
content:
application/json:
examples:
Example:
value:
request_id: aa253464-0bd0-467a-b24b-6159dcd7be60
data:
- email_id: 123456-1234-12
- schedule_id: 188262b6-f6cc-4c98-bbe6-84c39d1c0ef4
schema:
type: object
properties:
request_id:
type: string
example: aa253464-0bd0-467a-b24b-6159dcd7be60
data:
type: array
description: An array of `email_id/schedule_id` information in the same order as the payload.
items:
type: object
properties:
email_id:
type: string
description: The email_id of the email
schedule_id:
type: string
description: The schedule_id of the email (if `schedule` was passed, used to search/remove scheduled emails)
example:
- email_id: 123456-1234-12
- schedule_id: 188262b6-f6cc-4c98-bbe6-84c39d1c0ef4
- schedule_id: 789db207-5aba-4895-801b-4ebf1843721e
'400':
description: '400'
content:
application/json:
examples:
Example:
value:
request_id: 22e5acba-43bf-11e6-ae42-408d5cce2644
data:
error_code: E_ApiResponseCodes.ENDPOINT_PERMISSION_DENIED
error: You do not have permission to access this API endpoint
schema:
type: object
properties:
request_id:
type: string
example: 22e5acba-43bf-11e6-ae42-408d5cce2644
data:
type: object
properties:
error_code:
type: string
example: E_ApiResponseCodes.ENDPOINT_PERMISSION_DENIED
error:
type: string
example: You do not have permission to access this API endpoint
deprecated: false
/email/mime:
post:
tags:
- EMAILS
summary: Send a MIME email
description: Send an email by supplying a pre-encoded MIME string
operationId: send-mime-email
requestBody:
content:
application/json:
example:
mime_email: VG86IHRlc3RAZXhhbXBsZS5jb20KU3ViamVjdDogdGVzdApGcm9tOiBvdGhlckBleGFtcGxlLmNvbQoKdGVzdCBlbWFpbA==
schema:
type: object
required:
- mime_email
properties:
mime_email:
type: string
description: A valid MIME-encoded string that has been Base64 encoded
schedule:
type: string
description: A timestamp that when passed allows you to schedule an email for sending. Must be in the future and within the next 3 days.<br />The api response will include a `schedule_id` property which can then be used alongside webhooks (An `X-Smtp2go-Schedule-Id` header is added to the sent email corresponds to this id). A total of 50,000 emails can be queued at any one time.
fastaccept:
type: boolean
default: false
description: If true, the email will be accepted immediately and sent in a background process. Use webhooks if you need information about final delivery to the recipient. This will soon become the default method of sending via API.
responses:
'200':
description: Mime email sent
content:
application/json:
examples:
Example:
value:
request_id: aa253464-0bd0-467a-b24b-6159dcd7be60
data:
failed: 0
failures: []
succeeded: 1
schema:
type: object
required:
- request_id
- data
properties:
request_id:
type: string
example: aa253464-0bd0-467a-b24b-6159dcd7be60
data:
type: object
required:
- email_id
properties:
failed:
type: integer
example: 0
default: 0
description: 'The number of emails that failed to send.<br><br>Note: An email with multiple recipients is classed as 1 email. Only returned if ''fastaccept'' is false.'
failures:
type: array
description: An array containing any error messages encountered during sending. Only returned if 'fastaccept' is false.
succeeded:
type: integer
example: 1
default: 0
description: 'The number of emails that were successfully sent.<br><br>Note: An email with multiple recipients is classed as 1 email. Only returned if ''fastaccept'' is false.'
email_id:
type: string
example: 1u0SwL-B9zBpi9ffUq-JAB2
description: The email ID generated if successfully sent
schedule_id:
type: string
example: caa928f4-24ec-4a68-bcfc-1fd2596342f0
description: The schedule ID generated if queued for sending. Only returned if 'schedule' is passed.
'400':
description: '400'
content:
application/json:
examples:
Example:
value:
request_id: 22e5acba-43bf-11e6-ae42-408d5cce2644
data:
error_code: E_ApiResponseCodes.ENDPOINT_PERMISSION_DENIED
error: You do not have permission to access this API endpoint
schema:
type: object
properties:
request_id:
type: string
example: 22e5acba-43bf-11e6-ae42-408d5cce2644
data:
type: object
properties:
error_code:
type: string
example: E_ApiResponseCodes.ENDPOINT_PERMISSION_DENIED
error:
type: string
example: You do not have permission to access this API endpoint
deprecated: false
/email/scheduled/remove:
post:
tags:
- EMAILS
summary: Remove a scheduled email
description: Removes a scheduled email by ID
operationId: remove-scheduled-email
requestBody:
content:
application/json:
schema:
type: object
required:
- schedule_id
example:
schedule_id: fe7d54d0-8f06-40c5-a675-d72f183e8ebf
properties:
schedule_id:
type: string
description: The schedule_id returned from <code>/v3/email/scheduled/search</code> or the following endpoints [<code>/v3/email/send</code>, <code>/v3/email/mime</code>] (when <code>schedule</code> is passed)
responses:
'200':
description: Scheduled email removed
'400':
description: '400'
content:
application/json:
examples:
Example:
value:
request_id: 22e5acba-43bf-11e6-ae42-408d5cce2644
data:
error_code: E_ApiResponseCodes.ENDPOINT_PERMISSION_DENIED
error: You do not have permission to access this API endpoint
schema:
type: object
properties:
request_id:
type: string
example: 22e5acba-43bf-11e6-ae42-408d5cce2644
data:
type: object
properties:
error_code:
type: string
example: E_ApiResponseCodes.ENDPOINT_PERMISSION_DENIED
error:
type: string
example: You do not have permission to access this API endpoint
deprecated: false
/email/scheduled/search:
post:
tags:
- EMAILS
summary: Search schedule emails
description: Allows searching of scheduled emails
operationId: search-scheduled-emails
requestBody:
content:
application/json:
schema:
type: object
required: []
example:
schedule_id: 8fb29ea3-286d-493e-83c5-401f76859bb1
search: recipient@example.com
limit: 100
page: 2
properties:
schedule_id:
type: string
description: The schedule_id returned from the `/email/send` endpoint
search_subject:
type: string
description: The subject of the email you want to search for
search_recipient:
type: string
description: The recipient of the email you want to search for
search_sender:
type: string
description: The sender of the email you want to search for
limit:
type: integer
description: If passed will limit the search results
default: 1000
page:
type: integer
description: If passed will return the results of the specific page
responses:
'200':
description: Scheduled email results
content:
application/json:
examples:
Example:
value:
request_id: c2dca1b4-89b9-4dc7-bd82-a86b83b29d84
data:
- schedule_id: 4d3b03a7-8663-4592-899a-b479ba6fcba9
schedule: '2025-06-30T23:11:56Z'
sender: test@example.com
subject: test 1
recipients: test@example2.com
client_ip: 127.0.0.1
- schedule_id: 188262b6-f6cc-4c98-bbe6-84c39d1c0ef4
schedule: '2025-06-30T23:11:56Z'
sender: test@example.com
subject: test 2
recipients: test@example2.com
client_ip: 127.0.0.1
- schedule_id: 789db207-5aba-4895-801b-4ebf1843721e
schedule: '2025-06-30T23:11:56Z'
sender: test@example.com
subject: test 3
recipients: test@example2.com
client_ip: 127.0.0.1
schema:
type: array
items:
type: object
description: An array of emails scheduled to be sent
properties:
schedule_id:
type: string
description: A unique identifier for the scheduled_email
schedule:
type: string
description: A timestamp indicating when the email was scheduled. A total of 50,000 emails can be queued at any one time.
sender:
type: string
description: The sender of the scheduled email
subject:
type: string
description: The subject of the email
recipients:
type: string
description: The recipients the email is scheduled to send to
client_ip:
type: string
description: The IP address that scheduled the email.
'400':
description: '400'
content:
application/json:
examples:
Example:
value:
request_id: 22e5acba-43bf-11e6-ae42-408d5cce2644
data:
error_code: E_ApiResponseCodes.ENDPOINT_PERMISSION_DENIED
error: You do not have permission to access this API endpoint
schema:
type: object
properties:
request_id:
type: string
example: 22e5acba-43bf-11e6-ae42-408d5cce2644
data:
type: object
properties:
error_code:
type: string
example: E_ApiResponseCodes.ENDPOINT_PERMISSION_DENIED
error:
type: string
example: You do not have permission to access this API endpoint
deprecated: false
/email/send:
post:
tags:
- EMAILS
summary: Send a standard email
description: Send an email by passing a JSON email object
operationId: send-standard-email
requestBody:
content:
application/json:
schema:
type: object
required:
- sender
- to
example:
to:
- Jane Jones <jane@example.com>
sender: John Smith <john@example.com>
subject: My Test Email
html_body: <h1>Test <img src="cid:mypicture.jpg" /></h1>
text_body: Test
attachments:
- filename: report.pdf
mimetype: application/pdf
fileblob: bm90IGFjdHVhbGx5IGEgcGRm...
inlines:
- filename: mypicture.jpg
mimetype: image/jpeg
url: https://myserver.com/mypicture.jpg
schedule: 2025-09-10 13:15:00 +1200
properties:
sender:
type: string
description: The name and email address to send from, in the format `Name <name@example.com>`
to:
type: array
description: An array of names and email addresses (up to 100) to send to, in the format `Name <name@example.com>`
items:
type: string
cc:
type: array
description: An array of names and email addresses (up to 100) to CC, in the format `Name <name@example.com>`
items:
type: string
bcc:
type: array
description: An array of names and email addresses (up to 100) to BCC, in the format `Name <name@example.com>`
items:
type: string
subject:
type: string
description: The subject of the email to be sent, <strong>Note:</strong> if <code>template_id</code> if passed this field is ignored.<br /><br />If you would like to set a custom subject in the <code>template_data</code>, use a variable (<code>{{custom_subject}}</code> for instance) as the value of the templates <em>subject</em> and then set its value in <code>template_data</code> respectively.
html_body:
type: string
description: 'A HTML encoded email body. Either <code>html_body</code> or <code>text_body</code> is required if <code>template_id</code> is not passed. If <code>template_id</code> is passed this field is ignored.<br><br> <strong>Warning:</strong><ul><li>To correctly track clicking of URLs you must: <ul><li>Enable click tracking for the API key</li> <li>Insert a full anchor HTML element (not just the URL)</li> <li>Include "https://" at the start of the HREF property</li> </ul></ul>'
text_body:
type: string
description: A plain text email body. Either <code>html_body</code> or <code>text_body</code> is required if <code>template_id</code> is not passed. If <code>template_id</code> is passed this field is ignored.
custom_headers:
type: array
description: An array of custom header objects to be applied to the email. For example, a `Reply-To` email can be specified here, with header `Reply-To` and value `name@example.com`. For sending purposes the following headers are not allowed `Content-Type`, `Content-Transfer-Encoding` and `MIME-Version`.
items:
properties:
header:
type: string
description: Custom header to add to the email
value:
type: string
description: Custom header value to set
required:
- header
- value
type: object
attachments:
type: array
description: An array of attachment objects to be attached to the email
items:
properties:
filename:
type: string
description: The filename to use for this binary data
fileblob:
type: string
description: The Base64 encoded binary data of the file. Required if no url is specified.
mimetype:
type: string
description: The mimetype of the binary data
url:
type: string
description: A URL pointing to the attachment data. The data is directly retrieved by our system, and cached for fast re-use for 24 hours. Required if no fileblob is specified
required:
- filename
type: object
inlines:
type: array
description: An array of images to be inlined into the email. Use an image in content as `<img src="cid:filename"/>`
items:
properties:
filename:
type: string
description: The filename to use for this binary data
fileblob:
type: string
description: The Base64 encoded binary data of the file. Required if no url is specified.
mimetype:
type: string
description: The mimetype of the binary data
url:
type: string
description: A URL pointing to the attachment data. The data is directly retrieved by our system, and cached for fast re-use for 24 hours. Required if no fileblob is specified
required:
- filename
type: object
template_id:
type: string
description: The ID of the template you wish to use
template_data:
type: string
description: 'When a template_id is provided, include the pass-through values in the format `{"variable1": "value1", "variable2": "value2"}`'
format: json
schedule:
type: string
description: A timestamp that when passed allows you to schedule an email for sending. Must be in the future and within the next 3 days.<br />The api response will include a `schedule_id` property which can then be used alongside webhooks (An `X-Smtp2go-Schedule-Id` header is added to the sent email corresponds to this id). A total of 50,000 emails can be queued at any one time.
fastaccept:
type: boolean
default: false
description: If true, the email will be accepted immediately and sent in a background process. Use webhooks if you need information about final delivery to the recipient. This will soon become the default method of sending via API.
responses:
'200':
description: Email sent
content:
application/json:
examples:
Example:
value:
request_id: aa253464-0bd0-467a-b24b-6159dcd7be60
data:
succeeded: 1
failed: 0
failures: []
email_id: 1u0SwL-B9zBpi9ffUq-JAB2
schema:
type: object
required:
- request_id
- data
properties:
request_id:
type: string
example: aa253464-0bd0-467a-b24b-6159dcd7be60
data:
type: object
required:
- email_id
properties:
failed:
type: integer
example: 0
default: 0
description: 'The number of emails that failed to send.<br><br>Note: An email with multiple recipients is classed as 1 email. Only returned if ''fastaccept'' is false.'
failures:
type: array
description: An array containing any error messages encountered during sending. Only returned if 'fastaccept' is false.
succeeded:
type: integer
example: 1
default: 0
description: 'The number of emails that were successfully sent.<br><br>Note: An email with multiple recipients is classed as 1 email. Only returned if ''fastaccept'
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# Full source: https://raw.githubusercontent.com/api-evangelist/smtp2go/refs/heads/main/openapi/smtp2go-emails-api-openapi.yml